This is the "A Caprice with Ruins on the Seashore" by Francesco Guardi. Painted in the Italian north, Guardi was known for capturing the atmospheric and emotional qualities of a scene.
Here, we see a once glorious but now ruined folly on one of the islands in the Venetian lagoon. The crumbling ruins are emphasized by the trailing greenery and warm light, evoking an emotional response in viewers. It's a reminder of the inevitable passage of time.
Note how Guardi uses just a few strokes to suggest form - he was over 60 when he painted this in the late 1770s. Take a look at the two figures in the foreground, placed in a shaft of light. The arch behind them acts as a framing device, allowing the distant architecture to recede into the background.
The use of warm light and atmospheric perspective creates a sense of depth, drawing your eye into the scene. It's a beautiful example of Guardi's ability to capture the fleeting effects of light on the natural world.
A Caprice with Ruins on the Seashore hangs in The National Gallery on Trafalgar Square, London — free to enter. Point your phone at any artwork there and audioguide.london plays a free audio guide in six languages — no app download needed.